31321221 has 8 divisors (see below), whose sum is σ = 41913504. Its totient is φ = 20804880.

The previous prime is 31321219. The next prime is 31321229. The reversal of 31321221 is 12212313.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 31321221 - 2¹ = 31321219 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 31321221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31321229) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18015 + ... + 19676.

It is an arithmetic number, because the mean of its divisors is an integer number (5239188).

Almost surely, 2^31321221 is an apocalyptic number.

It is an amenable number.

31321221 is a deficient number, since it is larger than the sum of its proper divisors (10592283).

31321221 is a wasteful number, since it uses less digits than its factorization.

31321221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37971.

The product of its digits is 72, while the sum is 15.

The square root of 31321221 is about 5596.5365182405. The cubic root of 31321221 is about 315.2193684846.

Adding to 31321221 its reverse (12212313), we get a palindrome (43533534).

The spelling of 31321221 in words is "thirty-one million, three hundred twenty-one thousand, two hundred twenty-one".